I believe you should feed them a little piece every few days to start with and then as the weeks go by every 2 days then you can eventually feed them a little piece every day when their tums are used to it.
There's a good site which has a list of safe hamster foods:
https://erinshamsters.wixsite.com/ha...amsterfoodlist
All hamsters are different, if i give my hammy a bit of carrot he's not usually that interested and won't eat it all but if he gets a bit of broccoli he will sit there and eat it all!